Atomic layer deposition of boron-containing films using B{sub 2}F{sub 4}

• Published in: Journal of vacuum science & technology. A, Vacuum, surfaces, and films Vacuum, surfaces, and films, 2016-01, Vol.34 (1)
• Main Authors: Mane, Anil U., Elam, Jeffrey W., Goldberg, Alexander, Halls, Mathew D., Seidel, Thomas E., Current, Michael I., Despres, Joseph, Byl, Oleg, Tang, Ying, Sweeney, Joseph
• Format: Article
• Language: English
• Subjects: BORON; BORON CHLORIDES; BORON FLUORIDES; BORON OXIDES; CAPACITANCE; DENSITY FUNCTIONAL METHOD; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; MICROELECTRONICS; PRECURSOR; SILANES; SURFACES; X-RAY PHOTOELECTRON SPECTROSCOPY
• ISSN: 0734-2101; 1520-8559
• DOI: 10.1116/1.4935651

Ultrathin and conformal boron-containing atomic layer deposition (ALD) films could be used as a shallow dopant source for advanced transistor structures in microelectronics manufacturing. With this application in mind, diboron tetrafluoride (B{sub 2}F{sub 4}) was explored as an ALD precursor for the deposition of boron containing films. Density functional theory simulations for nucleation on silicon (100) surfaces indicated better reactivity of B{sub 2}F{sub 4} in comparison to BF{sub 3}. Quartz crystal microbalance experiments exhibited growth using either B{sub 2}F{sub 4}-H{sub 2}O for B{sub 2}O{sub 3} ALD, or B{sub 2}F{sub 4}-disilane (Si{sub 2}H{sub 6}) for B ALD, but in both cases, the initial growth per cycle was quite low (≤0.2 Å/cycle) and decreased to near zero growth after 8–30 ALD cycles. However, alternating between B{sub 2}F{sub 4}-H{sub 2}O and trimethyl aluminum (TMA)-H{sub 2}O ALD cycles resulted in sustained growth at ∼0.65 Å/cycle, suggesting that the dense –OH surface termination produced by the TMA-H{sub 2}O combination enhances the uptake of B{sub 2}F{sub 4} precursor. The resultant boron containing films were analyzed for composition by x-ray photoelectron spectroscopy, and capacitance measurements indicated an insulating characteristic. Finally, diffused boron profiles less than 100 Å were obtained after rapid thermal anneal of the boron containing ALD film.